How Big Do Pleco Fish Get?

The common plecostomus, or pleco, is a popular addition to home aquariums. Plecos are particularly popular with novice aquarists because they are hardy and peaceful, but can grow to a surprisingly large size.

  1. Adult Size

    • An adult plecostomus can easily reach a length of 10 to 18 inches within a span of several years. Some plecos have grown to two feet or more in length.

    Pet Store Plecos

    • Plecos sold in pet stores are often only one to two inches in length, and novice aquarists often mistakenly assume that this is their adult size. These fish are actually fry--rarely more than four months old.

    Tank Size

    • While pleco fry can survive in small tanks (10 to 50 gallons), they will eventually outgrow any aquarium smaller than 55 to 100 gallons. Because they grow quickly, it is best to introduce plecos to an adequately large tank from the start.

    Misconceptions

    • Plecos will not grow in proportion to the size of their tank; they will either reach their adult size or die prematurely from overcrowding. Plecos that are properly kept should survive 10 to 15 years.

    Smaller Species

    • Aquarists with small tanks should choose small bottom-feeders instead of common plecos. Some good alternatives are corydoras catfish and otocinclus catfish.